I am using Google Application Engine to host a web application and Google Cloud Storage to host documents.
I would like to keep track of:
Is it possible to tune Stackdriver for this purposes? And how? Is there a specific guide I can follow?
Give a look at Identity-Aware Proxy. Basically with IAP you should be able to control all the accesses to your application deployed within GCP. You can then tune your logging scope as described as follows: https://cloud.google.com/iap/docs/audit-log-howto.
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